U.S. patent number 6,368,301 [Application Number 09/471,053] was granted by the patent office on 2002-04-09 for catheter having a soft distal tip.
This patent grant is currently assigned to Advanced Cardiovascular Systems, Inc.. Invention is credited to Teresita R. Baerga, Rasean L. Hamilton.
United States Patent |
6,368,301 |
Hamilton , et al. |
April 9, 2002 |
**Please see images for:
( Certificate of Correction ) ** |
Catheter having a soft distal tip
Abstract
An intraluminal catheter comprising an elongated catheter shaft
having proximal and distal ends and at least one lumen, and a tip
member on a distal end of the catheter having a proximal end spaced
distally apart from the distal end of the catheter shaft.
Inventors: |
Hamilton; Rasean L. (Santa
Clara, CA), Baerga; Teresita R. (San Jose, CA) |
Assignee: |
Advanced Cardiovascular Systems,
Inc. (Santa Clara, CA)
|
Family
ID: |
23870074 |
Appl.
No.: |
09/471,053 |
Filed: |
December 21, 1999 |
Current U.S.
Class: |
604/103;
604/96.01 |
Current CPC
Class: |
A61M
25/0069 (20130101); A61M 2025/0081 (20130101); A61M
2025/1093 (20130101) |
Current International
Class: |
A61M
25/00 (20060101); A61M 029/00 () |
Field of
Search: |
;604/96.01,103,915,523,921,525,103.05,103.06 ;606/192,194 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3900635 |
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Jan 1989 |
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DE |
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0517075 |
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May 1992 |
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EP |
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2337094 |
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Apr 1999 |
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GB |
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WO 99/44666 |
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Feb 1999 |
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WO |
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Primary Examiner: Seidel; Richard K.
Assistant Examiner: Thanh; LoAn H.
Attorney, Agent or Firm: Coudert Brothers LLP
Claims
What is claimed is:
1. A balloon catheter having a distal end, comprising:
a) an elongated catheter shaft having a proximal end, a distal end,
a proximal shaft section, a distal shaft section, a guidewire
receiving lumen extending along at least a distal portion of the
catheter shaft to a port at the catheter distal end, and an
inflation lumen;
b) a tip member located at a distal end of the catheter and having
a proximal end spaced distally apart from the distal end of the
elongated catheter shaft and defining a gap therebetween; and
c) a balloon on the distal catheter shaft section and having an
inflatable interior in fluid communication with the inflation
lumen, and a distal balloon shaft section having an extending
portion with an interior surface extending longitudinally over the
gap and defining at least in part the guidewire receiving
lumen.
2. The catheter of claim 1 wherein the balloon inflatable interior
is spaced proximal to the distal end of the elongated shaft.
3. The catheter of claim 1, wherein the tip member has a lumen
extending therein in fluid communication with a lumen in the
elongated shaft.
4. The catheter of claim 1, wherein the tip member is softer than
the catheter shaft.
5. The catheter of claim 1, wherein the tip member is formed of a
polymeric material having a Shore Durometer hardness lower than a
Shore Durometer hardness of a polymeric material forming at least a
section of the catheter shaft.
6. The catheter of claim 1, wherein the proximal end of the tip
member is spaced apart from the distal end of the catheter shaft by
about 0.05 to about 0.3 mm.
7. The balloon catheter of claim 1, including a sheath which is
bonded to the catheter shaft and the tip member, and which has a
section extending from the distal end of the catheter shaft to the
proximal end of the tip member.
8. The balloon catheter of claim 1 wherein the balloon inner
surface is bonded to an outer surface of the catheter shaft and an
outer surface of the tip member.
9. The balloon catheter of claim 1 wherein the balloon distal shaft
section has a tapered outer surface.
10. The balloon catheter of claim 1, wherein the extending portion
of the distal balloon shaft section extends between a transverse
surface of the distal end of the catheter shaft and a transverse
surface of the proximal end of the tip member.
11. The balloon catheter of claim 10, wherein the inner surface of
the extending portion of the balloon distal shaft section is
substantially axially aligned with an inner surface of the tip
member.
12. The balloon catheter of claim 1 wherein the catheter shaft
comprises an outer tubular member defining the inflation lumen and
an inner tubular member disposed within at least a portion of the
outer tubular member and defining the guidewire lumen, wherein the
distal end of the inner tubular member is spaced apart from the
proximal end of the tip member.
13. The balloon catheter of claim 12 wherein the distal balloon
shaft section is secured to the inner tubular member.
14. A balloon catheter, comprising:
a) an elongated catheter shaft having a proximal end, a distal end,
an outer tubular member defining an inflation lumen, and an inner
tubular member having a distal end and disposed within at least a
section of the outer tubular member and defining a guidewire
lumen;
b) a tip member located at the distal end of the catheter and
having a proximal end spaced distally apart from the distal end of
the inner tubular member and defining a gap therebetween; and
c) a balloon on the distal catheter shaft section and having an
inflatable interior in fluid communication with the inflation
lumen, and a distal balloon shaft section having an extending
portion with an interior surface extending longitudinally over the
gap and defining at least in part the guidewire receiving lumen.
Description
BACKGROUND OF THE INVENTION
This invention relates to the field of medical devices, and more
particularly to a balloon catheter having a soft distal tip.
Catheters designed for intravascular procedures such as angioplasty
have a number of design considerations. Such catheters must be able
to transmit force along the length of the catheter shaft so that
the catheter can be pushed through the patient's vasculature.
However, the catheter shaft must also have sufficient flexibility
to allow it to track over a guidewire through tortuous vasculature.
The catheter also must be able to cross stenosed portions of the
vascular anatomy.
Prior art intravascular catheters have commonly included a soft
distal tip to prevent or minimize injury to the vessel during
advancement of the catheter therein. One difficulty has been
forming a connection between the soft tip and the catheter which is
sufficiently strong to prevent disengagement of the soft tip or
kinking at the junction between the soft tip and catheter shaft.
Additionally, it is necessary to balance the strength of the
connection between the soft tip and the catheter shaft with the
need to minimize the stiffness of the distal end of the catheter.
Minimizing the stiffness of the distal end of the catheter results
in improved maneuverability of the catheter.
Accordingly, it would be a significant advance to provide a
catheter with a soft tip having improved performance. This
invention satisfies these and other needs.
SUMMARY OF THE INVENTION
The invention is directed to an intraluminal catheter having a soft
distal tip, and generally comprising an elongated catheter shaft
having proximal and distal ends, at least one lumen, and a soft
distal tip member secured to the distal end of the catheter having
a proximal end spaced distally apart from the distal end of the
catheter shaft.
One embodiment of the invention is a balloon catheter generally
comprising an elongated catheter shaft having an inflation lumen
therein, a balloon on a distal shaft section in fluid communication
with the inflation lumen, and a soft distal tip member on a distal
end of the catheter. In accordance with the invention, the tip
member has a proximal end spaced distally apart from the distal end
of the catheter shaft. In one presently preferred embodiment, a
distal shaft section of the balloon is bonded to the distal end of
the catheter shaft, so that the balloon inflatable interior is
spaced proximal to the distal end of the elongated catheter shaft.
The balloon distal shaft section is also bonded to the proximal end
of the tip member, to thereby secure the tip member to the distal
end of the catheter. The tip member typically has a lumen in fluid
communication with a lumen of the catheter distal shaft
section.
The distal tip member is preferably softer than the catheter shaft,
to provide improved catheter maneuverability and decrease the risk
of damage to the patient's vessel during advancement of the
catheter therein. The tip member is typically formed of a polymeric
material having a Shore Durometer hardness which is lower than the
Shore Durometer hardness of the polymeric material forming at least
a section of the catheter shaft. The Shore Durometer hardness of
the polymeric material forming the tip member is about 35D to about
63D, preferably about 40D to about 55D. In a presently preferred
embodiment, the tip member is formed of a polyether block amide
polymer such as PEBAX (available from Autochem). However, the tip
member may be formed of a variety of suitable materials, including
polyolefin based copolymers such as a polyethylene based adhesive
polymers such as an ethylene-acrylic acid copolymer which is sold
commercially as PRIMACOR by Dow Chemical Co., and polyurethanes,
such as polyurethane block copolymers such as PELLETHANE (a
polyester based polyurethane, available from Dow Plastics).
In accordance with the invention, the tip member has a proximal end
spaced distally apart from the distal end of the catheter shaft. In
one embodiment, a gap exists between the distal end of the shaft
and the proximal end of the tip member, and the balloon distal
shaft section surrounds and extends over the gap. In another
embodiment, a portion of the balloon distal shaft section or an
intermediate member is disposed within the space between the distal
end of the catheter shaft and the proximal end of the tip
member.
A method of forming a distal tip of the invention generally
comprises positioning a proximal end of the tip member within a
balloon distal shaft section, so that the tip member proximal end
is spaced distally apart from a distal end of a catheter shaft
which is also within the balloon distal shaft section, and fusion
bonding the balloon distal shaft section of the catheter shaft and
the tip member. In one embodiment, the balloon material flows
during fusion bonding into at least a part of the space between the
proximal end of the catheter shaft and the distal end of the tip
member.
The catheter of the invention having a distal tip member spaced
distally from the distal end of the catheter shaft has excellent
crossability and trackability. The catheter has a smooth transition
in stiffness along the distal end of the catheter at the distal tip
member, to improve handling and performance and minimize kinking.
Additionally, the catheter has good tensile strength at the tip
member attachment, without disadvantageously increasing the
stiffness or profile of the distal end of the catheter. These and
other advantages of the invention will become more apparent from
the following detailed description and exemplary drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational view of a balloon catheter which embodies
features of the invention.
FIG. 2 is an enlarged, longitudinal cross sectional view of the
distal end of the catheter shown in FIG. 1, taken along lines
2--2.
FIG. 3 is a cross sectional view of the catheter shown in FIG. 2,
taken along lines 3--3.
FIG. 4 is a cross sectional view of the catheter shown in FIG. 2,
taken along lines 4--4.
FIG. 5 is a cross sectional view of the catheter shown in FIG. 2,
taken along lines 5--5.
FIG. 6 is an enlarged, longitudinal cross sectional view of an
alternate embodiment of the catheter of the invention, having
balloon shaft material between the catheter shaft and tip
member.
FIG. 7 is an enlarged, longitudinal cross sectional view of an
alternate embodiment of the catheter of the invention, having an
intermediate member between the catheter shaft and distal tip
member.
FIG. 8 is an enlarged, longitudinal cross sectional view of an
alternate embodiment of the catheter of the invention, having a
sheath surrounding the distal end of the catheter and the proximal
end of the distal tip.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 illustrates a balloon catheter 10 embodying features of the
invention, comprising an elongated catheter shaft 11 having a
proximal shaft section 12 and a distal shaft section 13, a tip
member 14, an inflatable balloon 15 on the distal catheter shaft
section 13 having an interior 16, and an adapter 17 on the proximal
catheter shaft section 12. In the embodiment illustrated in FIG. 1,
the catheter shaft 11 comprises an outer tubular member 18 having
an inflation lumen 19, and an inner tubular member 21 having a
guidewire receiving lumen 22 disposed within the outer tubublar
member. Guidewire 23, illustrated in FIG. 1 within guidewire
receiving lumen 22, extends to port 24 in the distal end of the tip
member 14. Balloon 15 has a working section 25, a proximal shaft
section 26 disposed about and secured to a distal portion of the
outer tubular member 18, and a distal shaft section 27.
As best illustrated in FIG. 2, showing an enlarged longitudinal
cross sectional view of a distal section of the catheter 10 shown
in FIG. 1 taken along lines 2--2, the proximal end of the tip
member 14 is spaced distally apart from the distal end of the inner
tubular member 21, and thus is not in contact therewith. In the
embodiment illustrated in FIG. 2, the distal end of the inner
tubular member 21 is disposed distally of the inflatable interior
16 of the balloon. The balloon distal shaft section 27 is disposed
about a distal portion of the inner tubular member 21 and a
proximal portion of the tip member 14. In a presently preferred
embodiment, the balloon distal shaft section 27 is secured to both
the distal portion of the inner tubular member 21 and the proximal
portion of the tip member 14, as for example, by fusion bonding. It
would be obvious to one of ordinary skill in the art that a sheath
40 located distally adjacent to the distal end of the balloon
distal shaft section 27 could be disposed about and secured to the
inner tubular member 21 or tip member 14 in place of the distal end
of the balloon distal shaft section 27.
As best illustrated in FIG. 2, tip member 14 has a lumen 28 in
fluid communication with guidewire receiving lumen 22. FIGS. 3, 4
and 5 illustrate transverse cross sectional views from the distal
portion of the inner tubular member 21 to the proximal portion of
the tip member 14 of the catheter 10, taken along lines 3--3, 4--4,
and 5--5, respectively. Tip member 14 is preferably a soft tip
formed of a polymeric material which is softer than the material
forming at least the distal portion of the inner tubular member 21,
which is secured to the balloon distal shaft section 27. The tip
member 14 illustrated in FIGS. 2 and 5 is formed of a single layer
of a material or a blend of materials. However, the tip member 14
may be a multilayered or multisectioned member (not shown).
In the embodiment illustrated in FIG. 2, a gap 31 is between the
distal end of the inner tubular member 21 and the proximal end of
the tip member 14. Gap 31 is defined between and in part by a
transverse surface 33 of the distal end of the inner tubular member
21 and a transverse surface 34 of the proximal end of the tip
member 14. Balloon distal shaft section 27 is in surrounding
relation to the distal end of the inner tubular member 21, gap 31,
and the proximal end of the tip member 14, so that the balloon
distal shaft section 27 extends over and in part defines gap 31. As
best illustrated in FIG. 4, showing transverse cross section of the
balloon distal shaft section 27 at the gap 31, the inner diameter
of the balloon distal shaft section is greater than the inner
diameter of the tip member 14.
In an alternative embodiment illustrated in FIG. 6, a portion 32 of
the balloon distal shaft section 27 extends between the distal end
of the inner tubular member 21 and the proximal end of the tip
member 14. The portion 32 is in contact with the transverse
surfaces 33 and 34, and has an inner surface 35 which defines a
section of the guidewire receiving lumen 22. In the embodiment
illustrated in FIG. 6, the inner surface 35 of the portion 32 of
the balloon distal shaft section 27 is substantially axially
aligned with the inner surface 36 of the tip member 14. The phrase
substantially axially aligned should be understood to mean that the
portion 32 of the balloon distal shaft section 27 and the tip
member 14 have the same inner diameter, or similar inner diameters
allowing for some slight variation in the inner surfaces 35/36. In
an alternative embodiment, the portion 32 of the balloon distal
shaft section 27 may fill only a portion of the space between the
inner tubular member 21 and the tip member 14, so that an inner
portion of the gap 31 remains (not shown).
In another embodiment illustrated in FIG. 7, intermediate member 41
is secured to and extends between the distal end of the inner
tubular member 21 and the proximal end of the tip member 14. In the
embodiment illustrated, the intermediate member 41 has a tubular
shape with a length equal to the length of the space between the
distal end of the inner tubular member 21 and the proximal end of
the tip member 14. In a presently preferred embodiment, the
intermediate member 41 is formed of a polymeric material which has
a Shore Durometer hardness which is lower than a Shore Durometer
hardness of the inner tubular member 21 and higher than that of the
tip member 14. However, the softness of the material may vary
depending on the length of the bond between the balloon distal
shaft section 27 and the tip member 14, and the desired use of the
catheter 10. The intermediate member 41 can be made from a variety
of suitable materials, such as a polyamide including a polyether
block amide, and polyethylene based adhesive polymers including
ethylene-acrylic acid copolymers such as PRIMACOR sold commercially
by Dow Chemical Co., and polyurethanes such as PELLETHANE. The
intermediate member 41 may be configured similar to the portion 32
of the balloon distal shaft section 27, as discussed above
regarding the embodiment shown in FIG. 6. In the embodiment
illustrated in FIG. 7, the intermediate member 41 has an inner
surface substantially axially aligned with the inner surface 36 of
the tip member 14 and an inner surface of the inner tubular member
21, as discussed above regarding the portion 32 of the balloon
distal shaft section 27 shown in FIG. 6. The intermediate member
41, and portion 32 of balloon distal shaft section 27, preferably
define annular lumens similar to those shown in FIGS. 3-5.
The space is sufficiently long so that the polymeric materials
forming the inner tubular member 21 and tip member 14 do not flow
into contact with one another during fusion bonding of the balloon
distal shaft section 27 thereto. The length of the space (i.e., the
length of gap 31, or portion 32, or intermediate member 41) between
the distal end of the inner tubular member 21 and the proximal end
of the tip member 14 may vary depending on the desired catheter
performance, the length of the balloon distal shaft section 27 and
tip member 14, and the method used to bond to tip member. The
length of the space is typically about 0.05 mm to about 0.75 mm,
more preferably, from about 0.05 mm to about 0.3 mm, preferably
about 0.05 mm to about 0.5 mm, most preferably about 0.1 mm to
about 0.3 mm. In a presently preferred embodiment, the balloon
distal shaft section 27 is about 1 to about 3 mm, preferably about
1.8 to about 2.2 mm. The tip member 14 is typically about 1 to
about 5 mm, preferably about 2 to about 3 mm. In the embodiment
illustrated in FIGS. 2, 6 and 7, the tip member 14 proximal end is
distal to the longitudinal center of the balloon distal shaft
section 27. However, in alternative embodiments, the tip member 14
proximal end may be located in various other locations along the
length of the balloon distal shaft section 27 (not shown).
The catheter shaft will generally have the dimensions of
conventional dilatation or stent deploying catheters. For coronary
use, the length of the catheter 10 may be about 90 cm to about 150
cm, and is typically about 145 cm. The outer tubular member 18 has
a length of about 15 cm to about 50 cm, an outer diameter (OD) of
about 0.03 inch to about 0.05 inch, and an inner diameter (ID) of
about 0.031 inch. The inner tubular member 20 has a length of about
15 cm to about 100 cm, an OD of about 0.024 in and an ID of about
0.017 in. The inner and outer tubular members may taper in the
distal section to a smaller OD or ID. Although not illustrated, the
catheter shaft inner tubular member, or outer tubular member, may
be made of multiple shaft sections joined together.
A method of forming a distal tip of a balloon catheter comprises
positioning a proximal end of a tip member and a distal end of a
catheter shaft within a lumen of a balloon distal shaft section, so
that the proximal end of the tip member is distally apart from the
distal end of the catheter shaft. The balloon distal shaft section
is fusion bonded to the catheter shaft and the tip member by
applying heat to at least a portion of the balloon distal shaft
section, to form a balloon catheter distal tip having the tip
member proximal end fusion bonded to the balloon distal shaft
section and spaced distally apart from the distal end of the
catheter shaft. Typically a mandrel is positioned within the inner
tubular member lumen 22 and the tip member lumen 28 before the
fusion bonding. In a presently preferred embodiment, a laser is
used to heat the material for fusion bonding, and laser parameters
such as focal length and power are selected to provide the desired
heat spread. The focal length is typically about 2.6 to about 3.25
inch, and the power is typically about 125 mw to about 170 mw for a
YAG (yttrium aluminum garnet) type laser. In one embodiment, the
balloon distal shaft section is heated so that the balloon material
flows into at least a part of the space between the proximal end of
the tip member and the distal end of the catheter shaft.
Alternatively, a removable spacer, configured to fit in the space
between the inner tubular member and the tip member, may be
disposed between the distal end of the inner tubular member 21 and
the proximal end of the tip member 14 during fusion bonding, or the
fusion bonding heat may be controlled, such that the balloon
material does not flow within the space between the inner tubular
member 21 and the tip member 14.
In the embodiments illustrated in FIGS. 2, 6 and 7, the outer
surface of the balloon distal shaft section tapers distally to a
smaller outer diameter. In one embodiment, the taper in the balloon
distal shaft section 27 is formed during fusion bonding as the
balloon polymeric material is heated and flows distally. Although
not shown in the figures, the portion 32 of the balloon distal
shaft section 27 may have a dip, i.e., a concave surface, formed as
the balloon polymeric material flows into the space between the
inner tubular member 27 and the tip member 14.
To the extent not discussed above, the various catheter components
may be formed of conventional materials. The inner tubular member
may be formed of a variety of conventional catheter shaft
materials, including PEBAX, Nylon, and high density polyethylene,
used alone or in blends or multilayered members. In a presently
preferred embodiment, the inner tubular member includes at least a
layer of PEBAX having a Shore Durometer hardness of about 60D to
about 72D.
While the present invention is described herein in terms of certain
preferred embodiments, those skilled in the art will recognize that
various modifications and improvements may be made to the invention
without departing from the scope thereof. For example, although
discussed primarily in terms of a catheter having an inner and
outer tubular member, it would be obvious to one of ordinary skill
in the art that the catheter shaft may alternatively have a dual
lumen shaft design. Moreover, although individual features of one
embodiment of the invention may be discussed herein or shown in the
drawings of the one embodiment and not in other embodiments, it
should be apparent that individual features of one embodiment may
be combined with one or more features of another embodiment or
features from a plurality of embodiments.
* * * * *